Liquid dispensing device

ABSTRACT

A burette consisting of a calibrated syringe chamber with a top flange and a reciprocable dispensing plunger. The plunger has a top actuator with a depending vertical rod on which is adjustably mounted a stop collar serving as a dispensing volume indicator and being engageable with said top flange to limit the upward extension of the plunger. The syringe chamber has a bottom outlet conduit including a check valve which opens when the plunger is drawn upwardly. The syringe chamber also has a discharge conduit at the level of the lowermost position of the bottom end of the plunger, the discharge conduit having a check valve which opens when the plunger is pushed downwardly for a discharge stroke. The chamber has a vent tube connected thereto at its lower portion. Below this the chamber has a peripheral rib, and O-rings are mounted on the chamber above and below the rib. An internally threaded annular cap surrounds the O-rings and acts to clamp the O-rings against the intervening rib when the cap is tightened on the neck of a container, so as to provide an air-tight seal relative to the container when the cap is tightened.

This invention relates to devices for accurately dispensing liquids, andmore particularly to dispensing burettes.

A main object of the invention is to provide a novel and improvedapparatus for accurately dispensing liquids, the apparatus being simplein construction, being easy to use, and offering a high degree ofreliability, speed, accuracy and convenience in use.

A further object of the invention is to provide an improved buretteapparatus which is inexpensive to manufacture, which is highly flexiblein use, and which may be safely used with a wide range of liquidmaterials, including concentrated acids, corrosive, dangerous, toxic, orodoriferous reagents, strong solvents, or the like, all of which may besafely and instantly dispensed with volumetric pipette precision fromtheir closed containers by means of te burette apparatus of the presentinvention.

A still further object of the invention is to provide a precise andjam-free dispensing burette apparatus of the plunger type, suitable foruse in accurately dispensing liquid materials from various types ofcontainers, such as bottles, flasks, beakers, tubes, etc., the apparatushaving wide versatility, being easy to keep clean, being automaticallybubble-free, and having a high repetitive accuracy.

Further objects and advantages of the invention will become apparentfrom the following description and claims, and from the accompanyingdrawings, wherein:

FIG. 1 is a side elevational view, partly in vertical cross-section, ofone form of burette apparatus constructed in accordance with the presentinvention, shown mounted in the neck of a reagent bottle.

FIG. 2 is a top plan view of the burette apparatus of FIG. 1.

FIG. 3 is a fragmentary vertical cross-sectional view taken through theneck portion of a screw cap reagent bottle in which is mounted anotherform of burette apparatus according to the present invention.

FIG. 4 is a fragmentary vertical cross-sectional view taken through theneck portion of a screw cap container in which is mounted still anotherform of burette apparatus constructed according to the presentinvention.

Referring to the drawings, and more particularly to FIGS. 1 and 2, 11generally designates one form of burette apparatus constructed inaccordance with this invention. The apparatus 11 comprises a main body12 of glass or other suitable material comprising a generallycylindrical vertical barrel portion 13 formed integrally with anenlarged hollow bottom stopper member 14 whose lower portion 48 isgenerally frusto-conical and downwardly tapering in shape so as tosealingly engage in the correspondingly shaped bore 15 of the neck 16 ofa conventional reagent bottle 17. The stopper member 14 has the upwardlytapering frusto-conical top wall 18 which is integrally formed with theoutwardly extending generally arcuate vent tube 19 communicating withthe interior of the stopper member, and hence with the upper portion ofthe associated bottle 17.

The barrel 13 is integrally formed at its top end with an annular flange20. Slidably and sealingly engaged in the barrel 13 is the syringeplunger 21, said plunger having eccentrically and rigidly secured to itstop end the relatively large operating disc 22. Rigidly secured to amarginal portion of disc 22 is a depending rod 23 which extends parallelto and adjacent to the barrel 13 and is provided with the adjustablestop collar 24, said collar being engageable with top flange 20 to limitthe upward extension of plunger 21. The collar is provided with adownwardly divergent frusto-conical bottom flange 25 extending adjacenta volumetric scale 26 inscribed on barrel 13. The collar is furtherprovided with a clamping screw 49 to lock it in an adjusted position onrod 23, said position corresponding to a predetermined desired dischargevolume of the burette apparatus, as indicated by the flange 25 on scale26 when the plunger 21 is in its lowermost position, as shown in FIG. 1.

Barrel 13 is integrally formed at a location substantially correspondingto the lowermost position of the bottom end 27 of plunger 21 with anoutlet conduit 28 extending perpendicular to the barrel, which is inturn integrally formed with an outer vertical portion 29 extendingupwardly and parallel to barrel 13. Said vertical conduit portion 29 isformed with a frusto-conical downwardly convergent ball seat 30 on whichis disposed a movable valve ball 31. Upward movement of said valve ballis limited by an inwardly projecting stop lug 32 formed integrally withthe inner wall of conduit portion 29. Conduit portion 29 terminates inan integral outwardly and downwardly inclined discharge conduit 33,which terminates substantially at the level of the ball seat 30.

The lower end of barrel 13 communicates with the top end of a generallyspherical ball valve housing 34 through a substantially frusto-conicaldownwardly convergent connecting wall element 47, said housing 34 beinglocated in the upper portion of hollow stopper 14. Integrally connectedwith the lower end of housing 34 in communication therewith is adepending vertical intake conduit 35 of sufficient length to extend tothe lower portion of the reagent bottle 17. A movable valve ball 36 isdisposed in the annular seat 37 defined at the top end of conduit 35.Upward movement of valve ball 36 is limited by an inwardly projectingstop lug 38 integrally formed on the inside wall of housing 34.

The reagent in the bottle 17 may be kept pure and free of moisture,interfering ions, or airborne contaminants by attaching a drying tubewith an appropriate filter or absorber to the air inlet tube 19, forexample, as diagrammatically shown at 50 in FIG. 4.

In operation, with the burette apparatus mounted in the neck 16 of thecontainer 17, all air bubbles are first removed and the dispensing tip33 is filled by pumping the plunger 21. With the collar 24 set at therequired position on rod 23, the plunger 21 is lifted until collar 24abuts flange 20. After a short period to allow for stabilization, theplunger 21 is depressed all the way, thereby delivering the desiredvolume of reagent through the tip 33.

It will be noted that on an upward stroke of plunger 21, suction isdeveloped in barrel 13, whereby atmospheric pressure forces liquid fromthe container 17 upwardly past ball valve element 36, whereas ball valveelement 31 is held closed by atmospheric pressure during the upwardstroke of said plunger. On the downward stroke of plunger 21, ball valveelement 36 is held closed by the pressure of liquid in the barrel,whereas ball valve element 31 is opened by the liquid pressure.

In the form of the invention shown in FIG. 3, the apparatus isconstructed to be mounted in the externally threaded neck 16' of acontainer 17', and an annular internally threaded sealing cap 40 isprovided, said cap being threadedly engageable on the neck 16'. Anannular outwardly projecting sealing rib 41 is integrally formed on thelower end portion of the plunger barrel, shown at 13', a short distanceabove the intake valve housing 34. The top wall of cap 40 is providedwith a central aperture 42 just large enough to pass the rib 41.Respective resilient deformable sealing rings 43 and 44 are providedabove and below the rib 41, the ring 43 preferably being split tofacilitate its installation around the barrel 13' above the rib 41. Anair-tight seal will be provided by the rings 43 and 44 when the cap 40is tightened on the neck 16'. The cap 40 is loosened before the upwardstroke of the plunger to allow atmospheric air to enter the top portionof container 17' to replace the liquid drawn into the barrel by saidupward stroke. The cap 40 is tightened before the downward stroke of theplunger.

In the form of the invention shown in FIG. 4, the barrel, shown at 13",is provided with a cylindrical bottom extension 45 formed to slidablyenter the bore 46 of the container neck 16'. An annular outwardlyprojecting sealing rib 41' is integrally formed on extension 45, andrespective resilient deformable sealing rings 43 and 44 are provided onextension 45 above and below the rib 41'. The cap 40 is arranged tocooperate with the rings 43, 44 and the sealing rib 41' in the samemanner as in the form shown in FIG. 3. An air vent tube 19, similar tothat provided in the form shown in FIG. 1, is integrally provided on theupper portion of extension 45, acting in the same manner as described inconnection with the embodiment of FIGS. 1 and 2.

It will be noted that in the various forms of the invention abovedescribed, the main portion of the apparatus is essentially of one-pieceintegral construction and is made so that it can be automatically freedof air. The side arm 28 is secured to the barrel at the level of thefully inserted plunger without constricting the barrel. The ball stops32 and 38 are integral with the walls of their associated housings 29and 34 and hold their associated valve balls close to their seats,reducing back flow. The flange 20 is fully ground on its top and bottomsurfaces through its complete angular extent of 360°, which assuresprecision dispensing even if the plunger is rotated during a dispensingaction.

The annular indicating flange 25 serves as a pointer and permits fineparallax-free adjustments relative to the volumetric scale 26.

While certain specific embodiments of an improved liquid dispensingburette apparatus have been disclosed in the foregoing description, itwill be understood that various modifications within the spirit of theinvention may occur to those skilled in the art. Therefore it isintended that no limitations be placed on the invention except asdefined by the scope of the appended claims.

What is claimed is: .[.1. A burette device comprising a verticalcylindrical syringe chamber provided at its top end with an outwardlyprojecting stop flange, a dispensing plunger slidably and sealinglymounted in said chamber and having an enlarged horizontal top actuatingportion, a depending vertical rod secured to said actuating portion andextending parallel to said chamber, a stop collar adjustably secured onsaid rod and being engageable with said stop flange to limit upwardextension of said plunger, a horizontal outlet conduit formed integrallywith said chamber substantially at the level of the bottom of saidplunger in its lowermost position, a vertical upstanding check valvechamber integrally formed on the outer end of said outlet conduit andbeing provided with an outwardly and downwardly inclined discharge tip,said check valve chamber being provided with an upwardly facing ballseat, a movable valve ball on said seat, the inner wall of the checkvalve chamber being integrally formed with an inwardly projecting stoplug overlying said ball and limiting upward movement thereof, means onthe lower end of said syringe chamber to sealingly support the syringechamber in the mouth of a liquid container, a check valve housing formedintegrally with the lower end of said syringe chamber, a dependingvertical intake tube formed integrally with and communicating with thebottom of said housing and defining a ball seat at its top end, amovable valve ball on said last-named seat, and an inwardly projectingstop lug integrally formed on the inside wall of said housing, overlyingsaid last-named valve ball and limiting upward movement thereof..]. .[.2. The structure of claim 1, and wherein said check valve housing issubstantially spherical in shape and is connected to the syringe chamberby a substantially frusto-conical upwardly flaring wall element..]..[.3. The structure of claim 2, and an outwardly projecting vent tubeintegrally formed with and communicating with the lower end of thesyringe chamber subjacent said wall element and above said sealingmeans..]. .[.4. The structure of claim 2, and wherein said sealing meanscomprises an enlarged hollow frusto-conical downwardly tapering stoppermember..]. .[.5. The structure of claim 2, and wherein said sealingmeans comprises an outwardly projecting annular sealing rib integrallyformed on the lower portion of the syringe chamber, annular resilientdeformable sealing rings surrounding the syringe chamber above and belowsaid rib, and an annular internally threaded cap member surrounding saidsealing rings and having a top wall provided with a central aperturejust large enough to pass said sealing rib..]. .[.6. The structure ofclaim 4, and an outwardly projecting vent tube on the top wall of saidstopper member..]. .[.7. The structure of claim 1, and a scale on thevertical syringe chamber..]. .Iadd.
 8. A burette device comprising avertical cylindrical syringe chamber provided at its top end with anoutwardly projecting stop flange, a vertically extending volumetricscale on said vertical syringe chamber having volume indications readingfrom smaller amounts to larger amounts in a downward direction, adispensing plunger slidably and sealingly mounted in said chamber andhaving an enlarged horizontal top actuating portion, a dependingvertical rod secured to said actuating portion and extending parallel tosaid chamber, a stop collar adjustably secured on said rod and beingengageable with said stop flange to limit upward extension of saidplunger, said stop collar serving as a mechanical stop for measuring thevolume to be dispensed and, when the plunger is in its lowermostposition, for accurately indicating on said scale the volume to bedispensed, a horizontal outlet conduit formed integrally with saidchamber substantially at the level of the bottom of said plunger in itslowermost position, said plunger being normally in said lowermostposition, a vertical upstanding check valve chamber integrally formed onthe outer end of said outlet conduit and being provided with anoutwardly and downwardly inclined discharge tip, said check valvechamber being provided with an upwardly facing ball valve seat, amovable valve ball on said seat, the inner wall of the check valvechamber being integrally formed with an inwardly projecting stop lugoverlying said ball and limiting upward movement thereof, means on thelower end of said syringe chamber to sealingly support the syringechamber in the mouth of a liquid container, a check valve housing formedintegrally with the lower end of said syringe chamber, a dependingvertical intake tube formed integrally with and communicating with thebottom of said housing and defining a ball seat at its top end, amovable valve ball on said last-named seat, and an inwardly projectingstop lug integrally formed on the inside wall of said housing overlyingsaid last-named valve ball and limiting upward movement thereof, whereinsaid sealing means comprises an outwardly projecting annular sealing ribintegrally formed on the lower portion of the syringe chamber,respective annular resilient deformable sealing rings surrounding thesyringe chamber above and below said rib, and an annular internallythreaded cap member surrounding said sealing rings and having a top wallprovided with a central aperture just large enough to pass said sealingrib. .Iaddend. .Iadd.
 9. A burette device comprising a verticalcylindrical syringe chamber provided at its top end with an outwardlyprojecting stop flange, a vertically extending volumetric scale on saidvertical syringe chamber having volume indications reading from smalleramounts to larger amounts in a downward direction, a dispensing plungerslidably and sealingly mounted in said chamber and having an enlargedhorizontal top actuating portion, a depending vertical rod secured tosaid actuating portion and extending parallel to said chamber, a stopcollar adjustably secured on said rod and being engageable with saidstop flange to limit upward extension of said plunger, said stop collarserving as a mechanical stop for measuring the volume to be dispensedand, when the plunger is in its lowermost position, for accuratelyindicating on said scale the volume to be dispensed, a horizontal outletconduit formed integrally with said chamber substantially at the levelof the bottom of said plunger in its lowermost position, said plungerbeing normally in said lowermost position, a vertical upstanding checkvalve chamber integrally formed on the outer end of said outlet conduitand being provided with an outwardly and downwardly inclined dischargetip, said check valve chamber being provided with an upwardly facingball valve seat, a movable valve ball on said seat, the inner wall ofthe check valve chamber being integrally formed with an inwardlyprojecting stop lug overlying said ball and limiting upward movementthereof, means on the lower end of said syringe chamber to sealinglysupport the syringe chamber in the mouth of a liquid container, a checkvalve housing formed integrally with the lower end of said syringechamber, a depending vertical intake tube formed integrally with andcommunicating with the bottom of said housing and defining a ball seatat its top end, a movable valve ball on said last-named seat, and aninwardly projecting stop lug integrally formed on the inside wall ofsaid housing overlying said last-named valve ball and limiting upwardmovement thereof, wherein said stop collar is provided with a downwardlydivergent frusto-conical annular bottom flange extending adjacent saidvolumetric scale. .Iaddend.